Container construction for pressurized fluids



A ril 17, 1962 M. E. WEBSTER ETAL 3,029,981

CONTAINER CONSTRUCTION FOR PRESSURIZED FLUIDS Filed May 28, 1959 9/6 I I l4 F1 INVENTOR MILO E. WEBSTER JOSEPH CASELLA ATTORNEYS 3,029,981 CONTAINER CONSTRUCTION FOR PRESSURIZED FLUIDS Milo E. Webster, Rochester, and Joseph Casella, Fairport, N.Y., assignors to Otto Bernz Co., Inc, Rochester, N.Y., a corporation of New York Filed May 28, 1959, Ser. No. 816,485 2 Claims. (Cl. 222-41) when excessive pressures develop in the container interior,

as, for example, when the container is subjected to unusually high temperatures. For this purpose an excess pressure relief valve is generally provided. The valve is conventionally spring loaded and will open when a predetermined pressure is exceeded in the interior of the container. Fluid is thus released from the container before an interior pressure is developed which would cause rupturing or explosion.

In recent years, a number of portable appliances which operate on LP gas, and particularly propane, have been widely marketed to the home consumer and various trades. These appliances include, for example, blow torches, lanterns, cook stoves, grilling devices, fire pots, leak detectors, and the like. The commercial success of these items has been predicated upon a'convenient and safe, readily available, and inexpensive source of LP gas.

Due to its highly inflammable nature, the sale and transportation of LP gas is strictly regulated. In the past only relatively large permanent, refillable cylinders were available for LP gas. bulky to be considered truly portable and the expense and inconvenience entailed in having the same refilled at an authorized station for the most part precluded their purchase and use by the ordinary amateur handy man and the general public. I

It was not until the development of the small portable throw-away LP cylinder that the use of propane operated tools and appliances became widespread among the average purchaser. The portable throw-away LP cylinder could be purchased in any ordinary hardware store, could be used interchangeably with various LP appliances, and

when the supply of LP gas was exhausted, could be thrown away avoiding the inconvenience and natural purchaser resistance to items that had to be returned and/ or refilled. In connection with these LP cylinders, just as with any other throw-away time, cost is a primary concern. A particular problem exists in keeping the cost of LP cylinders low enough so that the same may constitute a throwaway item since safety requires that they be constructed of heavy gauge steel, must meet extremely high safety requirements and have an excess pressure relief valve.

The conventional throw-away LP cylinders are generally made from sheet steel on a punch press using the conventional deep drawing techniques, a progressive die and a multiple number of drawing steps. The cylinders may be made with the upper portion and side walls punched from a single sheet of steel with the bottom separately punched and welded on, and preferably may be made in two halves which are brazed or welded together at a central joint extending transversely around the cylinder. A bushing for the attachment of a tap connection is pro- These cylinders were generally too connection with which the cylinder is to be used may be attached. The bushing is generally turned from metal stock and brazed to the top of the cylinder. Additionally, at the top of the cylinder adjacent to the bushing an excess pressure valve is provided. This valve is conventionally a valve spring loaded shut against the pressure in the interior of the cylinder and positioned in a machined housing, which is also brazed in the cylinder adjacent the bushing.

When excess pressure develops in the interior of the cylinder, as for example, when the cylinder is subjected to excessive heat, as for example, during a fire, and the pressure developed in the cylinder tending to force the valve open exceeds the pressure of the spring forcing the valve closed, the valve will be forced open releasing fluid from the interior of the cylinder until the pressure again falls below the determined safe maximum value at which the pressure of the spring acting on the valve exceeds the pressure in the interior of the container acting on the valve.

LP cylinders cannot be completely filled with a liquified petroleum product and may be only partially filled so that there exists within the container both a liquid and vapor phase. With the conventional positioning of the excess pressure safety valve, when the container was upright, the vapor would be in contact with the outlet from the excess pressure valve so that if material was released through this valve the same would flow out of the container in the manner of a dry feed discharge. On the other hand, if the container is lying on its side, material will flow out with a dry feed discharge or a wet feed discharge, depending on the position of rotation of the cylinder, e.g., depending on whether the excess pressure valve was above, to the side, or below the centrally positioned bushing. The reliability of operation of the valve could be effected by this. Furthermore, when the relief was of this dry feed type, very often the same would act as a jet, propelling the cylinder with great force, in a dangerous manner and discharging a well defined jet which could itself ignite into a hot, well-defined flame, thus increasing the fire and explosion hazard.

One'object of this invention is a container for pressurized fluid which avoids the above-mentioned disadvantages.

A further object of this invention is a portable LP gas cylinder which avoids the above-mentioned disadvantages and which may be more cheaply fabricated than the conventional LP gas cylinders, so as to be highly suited as a portable throw-away LP gas cylinder.

These and still further objects will become apparent from the following description read in conjunction with the drawings in which:

FIG. 1 is a vertical section of an embodiment of a portable LP gas cylinder, in accordance with the invention,

FIG. 2 is a plan view of the cylinder shown in FIG. 1.

Referring to the embodiment shown in the drawing, 1 is a cylindrical metal tube, which has been formed from a rectangular metal sheet, as for example, a rectangular sheet of steel about .023" thick, such as, by rolling, and welding together the overlapping edges to form the welded seam 2, which extends longitudinally along the tube wall. This welded seam may, for example, be formed with a small overlap of the edges and with a mesh Weld.

The top of the cylindrical tube 1 is sealed by the end closure cap 3 which may be stamped from sheet steel and which has an outer diameter which corresponds to the inner diameter of tube 1 so that the same may be positioned in the tube, as shown, and welded, as for example, With a lap seam weld at 4. The end closure cap 3 is provided with a central opening 5 into which the bushing 6 is positioned. The bushing 6 may have the structure as described in co-pending application Serial No. 747,974, filed July 11, 1958, and may be provided with the fiange 7 which is roll welded to the portion of the end closure 3 surrounding the opening 5. The bushing may be welded into position on the closure 3 prior to joining the closure 3 to the cylindrical tube 1.

The bushing 6 has an annular outer wall portion with the rolled-on male thread 8; is reverse bent at 9, and extends in the form of a central tubular stem 10 coaxially with the outer wall portion defining an annular space between it and the outer wall portion. The tubular stem extends through the opening to the interior of the container. The interior of the tubular stem is threaded at 11 and a' conventional automobile tire core valve 12 is screwed in place engaging these threads 11. Additionally, a rubber O-ring 13 and an aluminum retaining ring 14 are positioned in the tubular stern above the tire core valve.

The bushing may be produced from ordinary sheet steel of comparable thickness to that of the cylinder wall. The sheet steel may first be punched in the form of a disc and then, using a punch press machine and progressive die, as for example, with 12 stages, it may be punched out into the shape shown. After punching the same may be placed in a chucking machine and the external male thread 8 rolled on and the internal female thread 11 tapped into position.

The bottom of the cylindrical tube 1 is sealed with the end closure 15 having an outer diameter corresponding to the inner diameter of the cylindrical tube 1. The bottom closure is welded in place with a lap seam weld at 16. The end closure may be punched from sheet metal having a comparable or slightly thicker cross section than that of the tube 1.

The bottom closure 15, as may be noted, has a somewhat domed arched shape with a cylindrical rim or flange, at which the lap seam weld at 16 is effected. In the center of the end closure 15 an opening 17 is provided. This opening is preferably in axial alignment with the opening 5 and as the opening 5 is in the form of a round hole, though preferably of smaller diameter than the opening 5, an elongated tubular housing 18 is positioned in the hole 17 and sealed to the edges thereof by welding. This housing 18 preferably has the construction as set forth in co-pending application 747,974, and may thus be punched from a disc of sheet metal in a similar manner to the bushing 6. The housing 18 has a small central hole 19 and a female threaded portion 20 which is tapped in place. A pressure release valve 21 of conventional construction is screwed in place in this housing 18. The aforesaid pressure release valve has a central stem 22 extending coaxially in the center of the housing, a spring 23, and a closure member 24, with a rubber seal 25. The spring 23 presses the rubber seal 25 against the opening 19 sealing this opening in a pressure-tight manner. The housing 18 may be weldedin place on the end closure 15 prior to the end closure being welded to the tube 1.

After the entire cylinder is assembled and tire core valve 12 and the excess pressure relief valve 21 positioned in place, the cylinder may be charged with an LP gas such as liquified propane and is thus ready for sale and use in the manner of conventional portable throw-away LP cylinders.

When it is desired to connect an appliance to the cylinder, a tap connection on the appliance to be used is screwed over bushing 6 in engagement with the thread at 8. The tap connection has an elongated, hollow stem which extends into the tubular stem 10, in sealing engagement with the O-ring 13 pressing on the stem of the tire core valve 12, thus forcing the tire core valve open and allowing the LP gas to be tapped through the tubular stem 10 and the hollow stem of the tap connection and out of the tap connection. The tap connection and its use is conventional and well known and its embodiment is described in US. Patent 2,793,504.

When the pressure in the interior of the cylinder exceeds a pre-determined safe value, as for example, when a cylinder becomes over-heated, such as during a fire, the internal pressure of the fiuid will force the valve 21 open against the pressure of the spring 23, thus releasing fluid through the opening 19 and thus again reducing the pressure in the cylinder interior.

By having the discharge opening 19 for the excess pres sure valve at one end of the cylinder, and the normal discharge through the tubular stem 10 at the opposite end of the cylinder, a more reliable and trouble-free operation of the excess pressure valve is achieved. With the normal positioning of the cylinder, either upright or on its side, the discharge opening 19 for the excess pressure valve will be in contact with the liquid phase in the cylinder. The degree the excess pressure valve 21 will open will depend on the pressure build up in the interior of the cylinder and much better and more rapid relief of the excess pressure will be achieved for any degree of opening of this valve. The jet discharging from the excess pressure valve will be more diffused and will not be as definitely defined as is conventional so that even with a more eflicient release of the pressure, the tendency to jet propel the cylinder will be substantially decreased. Furthermore, the tendency of the jet to ignite will be decreased, and, if ignited, a much cooler flame will result.

While the invention has been described in detail with reference to the specific embodiments shown, various changes and modifications which fall within the spirit of the invention and the scope of the appended claims will become apparent to the skilled artisan. The invention, therefore, is only intended to be limited by the appended claims or their equivalents wherein we have attempted to claim all inherent novelty.

What is claimed is:

1. A portable throw-away LP gas cylinder comprising a cylindrical metal tube with a longitudinally Welded seam, a first end closure cap Welded on one end of said tube, a circular opening centrally defined through said first end closure, a bushing having an annular outer wall portion with an annular flange at one end inwardly reversed bent at the other end extending in the form of a central tubular stem coaxially with said outer wall portion and defining an annular space between it and said outer wall portion, said tubular stem coaxially extending in said circular opening, and said annular flange being Welded to the circumferentiial portion of said circular opening, a. closure valve positioned in said tubular stem, a second end closure cap welded on the opposed end of said tube, a second circular opening centrally defined through said second end closure, a tubular housing extending into said tube and welded to said second end closure at the circumferential portion of said second circular opening, and a spring loaded excess pressure safety valve in said tubular housing.

2. A portable throw-away LP gas cylinder, according to claim 1, in which said closure valve is an automobile tire core valve.

References Cited in the tile of this patent UNITED STATES PATENTS 1,243,733 Griflith Oct. 23, 1917 2,172,311 Thomas Sept. 5, 1939 2,240,791 Leeseberg May 6, 1941 2,500,119 Cooper Mar. 7, 1950 2,660,343 Charpiat Nov. 24, 1953 2,822,961 Seaquist Feb. 11, 1958 

